But, the study explains that genes have substantial influence on academic success. The kids were highly stable throughout schooling, meaning that most students who started off well in primary school continued to do well until graduation.

“Around two-thirds of individual differences in school achievement are explained by differences in children’s DNA,” said Margherita Malanchini, a psychology postdoctoral fellow at the University of Texas at Austin.

“But less is known about how these factors contribute to an individual’s academic success overtime,” Malanchini added.

However, that does not mean that an individual was simply born smart, researchers explained. Even after accounting for intelligence, genes still explained about 60 per cent of the continuity of academic achievement.

“Our findings should provide additional motivation to identify children in need of interventions as early as possible, as the problems are likely to remain throughout the school years,” said Kaili Rimfeld, a postdoctoral researcher at the King’s College London.

For the study, published in npj Science of Learning, the team analysed test scores from primary through the end of compulsory education of more than 6,000 pairs of twins.

Genetic factors explained about 70 per cent of this stability, while the twins shared environment contributed to about 25 per cent, and their nonshared environment, such as different friends or teachers, contributed to the remaining 5 per cent.

However, at times grades did change, such as a drop in grades between primary and secondary school. Those changes, researchers said, can be explained largely by nonshared environmental factors.